Definitely an interesting episode, and one of the "mystery" variety, where we don't learn the killer's identity until the final few minutes.
Mike's review (scroll down to episode 133) described the plot as "complicated", and that's an understatement! There's no way such a plot would see the light of day 2019, as editors would have had a field day with this one.
They crammed a ton of plot into these 48 minutes, thus leaving some unexplained points.
Scotty McBain was attempting to set up Diane Foxton for her father Harry's murder, but it seems the entire plan was far too complicated to work.
The "gimmick" of this episode involved the terminally ill Harry Foxton setting up a lottery, where 24 people bought $10,000 tickets, and each was assigned an hour of the day. The winner would be the one who had the hour Harry died. The prize would be $240,000, equating to about $1.3 million today.
Harry had ALS (Lou Gehrig's disease), but claimed he had cancer. It's unclear why he lied about his illness, given that both would be terminal.
Harry intended to kill himself and win his own lottery (bought through a proxy), believing he would die between midnight and 1am. However, McBain shot Harry's doctor (who gave Harry the suicide pill) dead, then took McBain and hid his body in a hot room, thus attempting to throw off the coroner, allowing Diane to win and become prime suspect.
McBain hired wiretapper/hitman Doug Listie to do his dirty work, but it's never made clear how Listie managed to break into McGarrett's office to bug it. It seemed all of Listie's break-ins had the same recognizable M/O, yet somehow the same wasn't noticed for McGarrett's office? (This was never explained.)
They also didn't explicity explain why Harry's doctor was murdered, but presumably it was so he wouldn't talk about the suicide pill, and give away that the time of death couldn't have been 10:30am.
All of the serial numbers on all the equipment used in the crimes (including guns) were stamped multiple times, but this particular detail was also never explained.
McBain was eventually tricked into showing up to retrieve tapes from Listie's hidden van, after McGarrett realized his office was bugged, and they set him up.
These "office bug" episodes actually annoy me, because they assume the bug has a spectacular range. Unless McBain/Listie were camped out very close to the Iolani Palace (unlikely), they couldn't have heard every word McGarrett was saying.
Doc was especially grumpy in the episode, for no apparent reason. At one point he complains, "This isn't a paradise, it's a shooting gallery!" He seems annoyed that McGarrett wants an exact time of death for Harry.
Despite the flaws, I still enjoyed the episode, and give it 3 stars.